PS9-28. Using Neonatal Piglet Hair to Explore Potential Connections Between Sow Stress and Prenatal Stress.

Abstract Hair cortisol and cortisone concentrations are growing in popularity as a non-invasive method to assess cumulative stress exposure in pigs. These concentrations measured in neonatal hair are uniquely related to prenatal stress and influenced by glucocorticoid concentrations in the amniotic fluid. The objective of this study was to determine the relationships between neonatal hair cortisol, hair cortisone, sow stress response in early gestation, and fetal programming of the adrenal gland. A total of 18 litters were selected based on the dams’ salivary cortisol response patterns following an acute social mixing event at 30 days of gestation. Within 24 h of farrowing and prior to piglet processing, one gilt and one boar piglet from each litter (n = 36 total) were euthanized for terminal sampling. Blood samples were collected for serum and plasma isolation. Plasma ACTH and serum cortisol were quantified by chemiluminescent immunoassays at the Michigan State University (MSU) Veterinary Diagnostic Laboratory. Hair was collected by using electric clippers and shaving the entire body surface. Neonatal hair samples were processed and quantified for cortisol and cortisone concentrations using commercially available ELISAs (Arbor Assays) by Stress Bioanalytics (Oswego, NY). Cross sections of adrenal tissue were placed into RNALater (Qiagen) during sampling and later processed to isolate RNA using RNeasy Mini Kit (Qiagen). Total RNA was sequenced in 2x150 bp format on an AVITI instrument by the MSU Research Technology Support Facility. Generated reads were trimmed, aligned to the Sus scrofa 11.1 reference genome, and normalized gene counts obtained using DESeq2. For this study, only transcript abundance of genes critical to glucocorticoid regulation and synthesis were examined. These genes included FKBP5, NR3C1, HSD11B1, STAR, MC2R, CYP11A1. Relationships of all measures were assessed using Pearson correlation testing. The acute stress response of the dams at mixing was significantly correlated with neonatal serum cortisol (R = 0.37, P = 0.027). Hair cortisone and cortisol concentrations were highly correlated (R = 0.78, P < 0.001), and hair cortisol concentration was correlated with neonatal plasma ACTH concentration (R = -0.39, P = 0.017). Transcript abundance of adrenal HSD11B1 was significantly correlated with both acute stress response of the dam in early gestation and neonatal hair cortisone concentration (R = 0.43, P = 0.041; R = 0.43, P = 0.039, respectively). Results suggest that piglets from dams with a stronger stress response in early gestation are exposed to higher glucocorticoids which may subsequently influence neonatal adrenal HSD11B1 expression. The HSD11B1 gene codes for the reductase enzyme that converts inactive cortisone to active cortisol. Given that maternal stress was correlated with both higher adrenal HSD11B1 transcript abundance and higher circulating serum cortisol in the neonate, HSD11B1 is a promising gene of interest for fetal programming of offspring stress regulation.